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Re: 980223: problem with nc_redef

>To: address@hidden
>From: Hartmut Freihofer <address@hidden>
>Subject: problem with nc_redef
>Organization: Forschungsinstitut fuer Kerntechnik und Energiewandlung e.V., 
>Abt. Wissensverarbeitung und Numerik
>Keywords: 199802231650.JAA06505

Hi Hartmut,

> i have a problem defining a new variable in an existing netCDF file
> which already contains data.
> 
> I use the netCDF version 3.4a and the Visual C++ Compiler 5.0.
> 
> I tried to make a short example showing my problem:
> 
> //BOF
> #include "netcdf.h"
> 
> int main(void){
> 
>       int ncstatus;
>       int ncid;
> 
>       ncstatus = nc_create("test.cdf", NC_CLOBBER , &ncid);
> 
> 
>       int ncidDim_Time;
>       ncstatus += nc_def_dim( ncid, "Timesteps", NC_UNLIMITED,
> &ncidDim_Time);
>  
>       int time_dimids[1];
>       int ncid_Time;
>       time_dimids[0]=ncidDim_Time;
>       ncstatus +=nc_def_var( ncid, "Time", NC_INT, 1, time_dimids, 
> &ncid_Time);
> 
>       int ncid_First_Var;
>       ncstatus += nc_def_var( ncid, "First_Var", NC_FLOAT,1,time_dimids, 
> &ncid_First_Var);
> 
> //put some data in it:
>       nc_enddef(ncid);
> 
>       size_t beg[1];
>       nc_inq_dimlen( ncid, ncid_Time, &beg[0]);
> 
>       size_t count[1];
>       count[0]=3;
>       long times[3]={1,2,3};
>       ncstatus += nc_put_vara_long(ncid, ncid_Time, beg, count, times);
> 
>       float data[3]={4.5,5.5,6.5};
>       ncstatus += nc_put_vara_float(ncid, ncid_First_Var, beg, count, data);
> 
> 
> //append another var:
>       nc_redef(ncid);
> 
>       int ncid_Second_Var;    // <<<<<<<<<<<<<<<< cdf file corrupts here! 
> >>>>>>>>>>>>>>>>>>
>       ncstatus += nc_def_var( ncid, "Second_Var", NC_FLOAT,   1,      
> time_dimids, 
> &ncid_Second_Var);
> 
>       nc_close(ncid);
> 
> return ncstatus;
> }
> //EOF
> 
> Is this a problem of mine (what mistake did i make)?
> Is it possible at all?

I was able to compile and run this program with the Sun C++ compiler,
and it worked fine, with the expected result from "ncdump test.cdf".

So this may be a platform-specific bug.  We will try to reproduce the
problem on an NT platform with Visual C++ 5.0, so we can determine the
cause.

Thanks for reporting the problem.

--Russ

_____________________________________________________________________

Russ Rew                                         UCAR Unidata Program
address@hidden                     http://www.unidata.ucar.edu